This application relates to photographic film coating apparatus, and more particularly to apparatus for applying protective coating to the surfaces of roll film, such as 35 millimeter processed film strips or other strip film material.
It is known that ultraviolet curable coating materials of the kinds described in the U.S. Pat. Nos. 4,049,861 of Nozarre, issued Sept. 20, 1977 and Lien et al, 4,049,861 issued May 22, 1979, have particular advantage as an abrasion-resistant coating for photographic films. Such protective coating materials are marketed in the United States by Minnesota Mining and Manufacturing Company under the trade name 3M Photogard and consist of an optically clear protective coating which is highly resistant to abrasion, to static electricity, to fingerprints, and to a wide variety of solvents.
In the photographic processing industry, it is common to assembly processed films, such as strips of color negative material, in serial or end-to-end relation, joined by paper splices, and wound as a roll on a spool, for unwinding and delivery to a printer. Commonly, such film come in various lengths, such as 36 exposure, 24 exposure, 20 exposure lengths, etc., which are then connected end to end by paper splicers so that a large number of such films, for example, negatives, can be handled for printing at one time. However, the film may consist of 100 foot lengths of microfilm material or 1,000 or 2,000 foot reels of motion picture film. Commonly, the paper splices connecting the adjacent ends of the strips, are applied to the emulsion sides of the films to the leader or trailing ends of the films beyond the image areas, and after the completion of the processing, including the printing where desired, the strips are again severed for packaging and return to the individual customer.
It has been found highly advantageous to apply a ultraviolet curable hard coating to such film of the general kind described above, and it not only reduces the likelihood of scratching of the film, but also reduces dust, makes fingerprints easy to wipe off, reduces static electricity which attracts dust and dirt, and otherwise protects and preserves the film. Further, such coating has been found to provide enhanced printing qualities to the film.
There is therefore a need for a relatively low cost simple and yet effective apparatus for applying protective coating to spools or reels of film, curing such coating, and returning the film to a take-up reel for subsequent processing, such as printing. It has been found that it is undesirable to coat the film with protective coating material in the region of the splices. Coating the splices adds an undesirable thickness or buildup in that region. More importantly, however, is the fact that the coating material tends to be absorbed by the splice or at least accumulated in the region of the splice, and frequently does not cure within the time allotted for the curing of the coating on the remaining portion of the film. Therefore, it has been necessary in the past from time to time to insert interleaf papers manually at the splice region where the splice occurs during the respooling or rewinding operation, to prevent the adjacent turn or layer of film from contacting the uncured or wet coating at the splice region. For this reason, there also exists a need to provide for automatic splice detection and control apparatus by means of which the splice is caused to pass through the coater without the accumulation of any appreciable coating in the splice region, and thereafter automatically to reestablish coating following the passage of the splice.